Prior-art respiration systems have, in general, a breathing circuit with an expiration branch and an inspiration branch, into which the gas components necessary for respirating the patient are introduced by means of a metered supply of fresh gas. If such a respiration system is used in the area of anesthesia, the breathing gas present in the breathing circuit is additionally enriched with an anesthetic. The respiration system is also called an anesthesia system in this case. The two terms are used as synonyms in this description, because the two types of systems differ essentially only by the additional supply of the anesthetic, but they otherwise have a very similar design.
Due to the metered supply of fresh gas (with or without anesthetic), the quantity of breathing gas consumed by the patient is replenished again and, in addition, possible leaks within the respirator are compensated. It is important especially in case of anesthesia to achieve the most effective utilization possible of the fresh gas, in which the anesthetic is also contained, in order to minimize the anesthetic consumption, on the one hand, and to protect the environment, on the other hand.
A so-called rebreathing system, in which CO2 is removed from the expired (expiratory) breathing gas by means of a CO2 absorber and the remaining breathing gas can again be added to the inspiratory breathing gas, is preferably used in the respiration system according to the present invention. Such a breathing system can be operated, in principle, in a half-closed mode of operation or as a largely closed breathing circuit. In the half-closed mode of operation, the quantity of fresh gas added to the breathing circuit exceeds the quantity that is taken up by a patient. The excess breathing gas is released from the breathing circuit into an anesthetic gas scavenging system during the patient's expiration phase. In the mode of operation of the closed breathing system, the breathing gases are essentially reprocessed by the CO2 absorber. A suitable absorbent, for example, soda lime, is used for this. The mode of operation with closed breathing circuit is preferably used in anesthesia systems.
As was explained above, the breathing circuit of prior-art respiration systems comprises an expiratory breathing gas channel (expiration branch for short) and an inspiratory breathing gas channel (inspiration branch for short) for providing breathing gas for the patient. The inspiration branch and the expiration branch are connected to one another at their patient-side ends via a so-called Y-piece, which is used via a connected flexible tube to pass on breathing gas to the patient.
The breathing circuit usually has, besides, a breathing gas delivery unit (breathing drive) and a volume flow sensor in the inspiration branch, the breathing gas delivery unit being controlled on the basis of the output signals of the volume flow sensor. A volume of breathing gas is displaced into the patient in such respiration systems during the phase of inspiration and a volume of breathing gas expired by the patient is displaced back again into the breathing circuit of the respiration system during the phase of expiration. However, the displacement of the breathing gas volume during the phase of expiration is not usually supported, so that the expiratory resistances present in the respiration system must be overcome by the patient himself during the expiration by the patient. These expiratory resistances lead to an unintended prolongation of the duration of the phase of expiration (compared to an unhindered expiration of the breathing gas volume by the patient) and to excessive fresh gas consumption when the breathing gas is partially drawn off through the breathing gas or gaseous anesthetic escape line to reduce the expiratory resistances, as a result of which higher costs are caused and the environment is needlessly polluted by removed mixtures of gaseous anesthetics especially in the area of anesthesia because of the increased anesthetic consumption.
EP 2 201 979 A1 discloses a respiration system with a breathing circuit and with a respirator connected with the breathing circuit. The gas flow through the respirator and through the breathing system can be controlled by means of valves. U.S. Pat. No. 7,870,857 generally describes a respiration system and especially different embodiments of a breathing system, which is provided between the respirator and the mouthpiece of the patient and comprises an air humidifier.
DE 100 41 007 C1 pertains to a process for controlling a respirator, by means of which improved utilization of the fresh gas and reduction of the expiratory resistances in the breathing circuit of the respirator are achieved by a maximum percentage of the breathing gas expired by the patient being returned to the patient via a breathing gas delivery unit and at the same time only a minimum percentage of the expired breathing gas being removed unused into the environment via a gaseous anesthetic drain line. At the same time, the minimum end-expiratory pressure (PEEP—Positive End Expiratory Pressure) can be kept as low as possible. According to DE 100 41 007 C1, this is achieved by the breathing gas delivery unit present in the inspiration branch being driven down in this case at a rate that is obtained from the sum of the volume flow expired by the patient and the fresh gas volume flow supplied. A maximum percentage of the breathing gas volume expired via the expiration branch reaches in this manner at first the breathing gas delivery unit and is displaced back to the patient through the inspiration branch during the subsequent phase of inspiration.
The breathing system, which is preferably designed as a rebreathing system, of the above-described respiration system can be detachably coupled with the housing of the respirator. The breathing system, or the essential components of the breathing system are contained in a separate breathing system housing, which can be coupled with the housing of the respirator. The breathing system housing can be placed, for example, on the housing of the respirator or inserted or pushed into this housing from the top or from the side.
The components of the breathing system may comprise essentially the components of the rebreathing system (or non-rebreathing system), a CO2 absorber, means for humidifying and heating the breathing air, various valves and pneumatic sensors as well as the corresponding connection pipes and connection tubes. In addition, the breathing system housing is provided with ports for the inspiration branch and the expiration branch of the patient tube system, which lead to the patient and are connected via the Y-piece described with a breathing mask for the patient to be respirated. In addition, a plurality of pneumatic ports are provided on the breathing system housing for connection to the housing of the respirator or anesthesia apparatus.
The housing of the respirator or anesthesia apparatus preferably contains a means for feeding fresh gas, means for feeding the anesthetic, a breathing gas delivery means, various pressure and volume sensors, a plurality of non-return valves, as well as all essential electrical and electronic components. Furthermore, the respirator is equipped to be connected to various means for controlling and monitoring respiration.
The purpose of the possibility of making a separation in space and in terms of function between the breathing system and the respirator is that the breathing system can be cleaned and sterilized separately from the respirator, which is important because the respirator cannot be sterilized due to the electrical and electronic components contained therein. If the respirator were exposed to the high temperatures of the sterilization process, undesired aging or failure of these components would inevitably occur.
It is apparent that the breathing system described has pneumatic and non-pneumatic connection to the respirator (therapy device). These connections are formed by so-called connectors, which usually have a “male” connector element and a “female” connector element. The combination of a male connector element and a female connector element is hereinafter also called connector system. One of the connector elements is provided on the housing of the system, while the respective corresponding connector element is provided at a corresponding location on the housing of the respirator. The connector systems and the elements thereof may be embodied by plugs, sockets, etc. When the breathing system is coupled with the respirator, the male and female connector elements that belong together mesh with one another, as a result of which at least two pneumatic connections are formed between the respirator and the breathing system.
It is apparent, furthermore, that after the breathing system is uncoupled or removed from the respirator, one of the connector elements (preferably the male element) of the connector systems remains in the housing of the respirator, because these elements are nondetachably connected to the housing of the respirator. The connector elements of the respirator and the internal lines, tubes, pipes or sensors connected thereto cannot be sterilized, because the respirator as a whole cannot be sterilized. Consequently, if bacteria, viruses or other contaminants adhere to the connector elements (and to the lines, tubes or sensors connected thereto) of the respirator, these can spread (when the breathing system is connected to the respirator) into the cleaned and sterilized breathing system.
Furthermore, the problem that the volume flows frequently flow in both directions through the respective connectors occurs in all prior-art respiration systems. In other words, expiratory air can flow from the breathing system into the respirator and then (for example, after CO2 absorption) back into the breathing system in the opposite direction through one and the same connector. Due to the oscillating motion of the volume flow through the respective connectors and through the lines connected thereto, the accumulation of bacteria, viruses and other contaminants contained in the expiratory air in the connectors as well as in the lines connected thereto is further intensified. This represents a problem especially for the respirator, because this—contrary to the breathing system—cannot be sterilized. Furthermore, the various sensors (especially the pressure sensors), which are located in the housing of the respirator, are coupled with the breathing system via separate connectors in respirators according to the prior art. This means that the measuring lines of the pressure sensors of the respirator are connected via respective connectors to the expiratory and inspiratory lines of the breathing system. If bidirectional or at least oscillating volume flows likewise take place in these lines, this may also lead to an accumulation of bacteria and viruses at least in the measuring lines and in the connectors of the respirator. These bacteria and viruses may greatly proliferate under favorable conditions (temperature and humidity of the air) and subsequently spread in the previously sterilized breathing system during the respiration of a patient. In addition, the measuring lines may be clogged by contaminants to such an extent that reliable measurements cannot be guaranteed any longer.